Rotor for dynamo-electric machines.



H. H. WAIT.

ROTOR FOR DYNAMO ELECTRIC MACHINES.

APPLICATION FILED JAN. 28, 1907.

Patented Apr. 4, 1911.

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H. H; WAIT. ROTOR FOR DYNAMO ELECTRIC MACHINES.

APPLIO ATION FILED JAN. 28,1907.

Patented Ap r.4, 1911.

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%1FlIlllllllllllllllllllllllllllllllll$3lflnllllllllllflllimiEHIIWILQ1HIIHHlIlllllllllllllllllllllllllll IHENRY H. WAIT, OF CHICAGO, ILLINOIS.

ROTOR FOR DYNAMO-ELECTRIC I-EACHINES.

To all whom it may concern:

Be it known that I, HENRY H. WAIT, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvementin Rotors for Dynamo-Electric Machines, of which the following is a full, clear, concise, andexact description.

My invention relates to a rotor for dynamo electric machines, and moreparticularly to an improved construction for the rotary field magnets ofalternating current generators of the high speed type. The rotors ofsuch machines, which are intended to be directdriven by steam turbines,are subjected to enormous centrifugal strains, and the problem ofproviding adequate mechanical support for the windings of such rotors,without violating the principles of good electrical design, is onepresenting many ditiiculties, which it is the object of this in ventionto overcome.

In accordance with my invention, the endconnecting portions of thewinding are supported by retaining members at the ends of the rotordisposed radially between the successive groups of end-connectors, saidend connectors lying in circumferential grooves or channels thusprovided between said retaining members. Keys are provided which fitover the conductors in the circumferential channels, these keysinterlocking with the projecting portions of the metal ribs betweenwhich said channels are formed. These keys may run either longitudinallyor circumferentially of the rotor surface, as will be described. Thestress due to circumferential force is thus transmitted to and sustainedby the radial retaining members or plates, which carry thecircumferential stress Well toward the center, where the ring or hubportions are not too greatly strained by their own centrifugal force. Anironclad rotor of good electrical design and very great mechanicalstrength is thus secured.

My invent-ion will be explained in detail, and further features thereofwill be particularly pointed out, by reference to the accompanyingdrawing, in which,

Figure 1 is a longitudinal sectional View of a portion of the end of arotary field magnet for a turbo-alternator; Figs. 2 and 3 are detailsillustrating the manner in which the end connecting portions of thecopper conductors may be spliced together; Figs. 4 and Specification ofLetters Patent.

Application filed. January 28, 1907.

Patented Apr. 4., 1911.

Serial No. 354,375.

5 are similar details illustrating how a conductor at the bottom of oneof the channels may be electrically connected to another conductor atthe top of the channel; Fig. 6 is a detail view of a portion of thesurface at the end of the rotor, developed into a plane, to show thedisposition of the conductors and the keys for holding them in theirslots or channels; Fig. 7 is a view similar to Fig. 6, but showing amodified construction in which the keys for holding the end-connectingportions of the conductors run longitudinally of the rotor, crossing allof the end-connections; Fig. 8 is a longitudinal sectional view of aportion of the end of the rotor constructed upon the modified plan shownin Fig. 7 Figs. 9 and 10 are similar views showing differentconstructions of the end plates or disks in which the circumferentialchannels for the end connections are provided; Fig. 11 is a crosssectional view of the form of the rotor illustrated in Figs. 7 and 8,the section being taken on the staggered line 1111 of Fig. 7; Figs. 12,13, 14 and 15 show plates of various forms; Fig. 16 illustrates a meansfor forcing the keys or wedges down in the slots and compressing theconductors underneath as much as possible, leaving room for theinsertion of supplemental wedges above the shoulders of the keys to holdsaid keys in their depressed position; Fig. 17 is a longitudinalsectional view of a portion of the surface showing one of thelongitudinal keys and the supplemental key in connection therewith; Fig.18 is a portion of the surface of the rotor shown in Figs. 7 8 and 11,with parts broken away to illustrate the application of certainfillerblocks which are intended to be inserted in the channels betweenthe different keys; and Fig. 19 is a detail view of one of thesefillerblocks.

The same letters of reference indicate the same parts wherever they areshown.

Referring first to Figs. 1 and 6, the rotor comprises a core a of theusual laminated construction, the core disks being assembled upon ashaft 5. The core is provided with longitudinal channels a at itsperiphery, these channels being shown as grooves or slots open at thetop and separated by intervening teeth a as shown in Figs. 6 and 11. Theconductors of the winding are disposed in these longitudinal grooves.The active portions a of the winding in the longitudinal grooves areunited at the ends by end-connecting portions a", which, in accordancewith my invention, are disposed in transverse channels or grooves a"extending circumferentially about the periphery of the rotor near theends thereof and uniting the longitudinal channels in pairs. Thecircumferential transverse channels which receive the end-connectingportions of the winding are separated by transverse metal ribs 0, whichmay be and preferably are disks or plates assembled upon the shaft atthe end of the rotor, these plates being disposed alternately betweenthe end-connections and projecting radially beyond the outer surface ofsaid end-connections. Metal keys f are provided which interlock with theprojecting portions of the ribs or plates between the end-connections,these keys overlying said connecting portions a. of the winding andserving to retain them in place against centrifugal force. As shown inFigs. 1 and (3, the inner sides of the circumferential connectinggrooves are undercut to receive the shouldered portions j of thecircun'iferential keys. The longitudinalgroan in the core receiving theactive portions or. the winding are also filled at the top bylongitudinal keys f sliding into undercut grooves near the tops of thesechannels. The peripheries of the keys and disks at. the ends of therotor are preferably grooved circumferentially at the outer edge toincrease the heat radiating surface; and i may also provide radiatingventilatil'ig channels a c communicating with the interior longitudinalventilating bore (Z, as shown in Fig. 8.

The circumferential channels for the endconnections are formed by spacesbetween the circular plates 0. Various forms of these plates are shownin the drawings. In general, each plate will have a large tooth or lug0* (Figs. 6 and 11) extending over a considerable arc of itscircumference from the mouth of a longitudinal channel on one side ofthe rotor to the mouth of the corresponding channel symmetricallylocated on the other side of the rotor; and each plate will further havesmaller individual teeth a projecting between the longitudinal portionsof those turns of the winding which lie outside those immediatelyembracing the large lug. The first few retaining plates lying nearestthe core could be made of magnetic material, such as steel, in whichcase they will augment the magnetic carrying capacity of the core, butwill also increase the leakage. I prefer, therefore, to make only one ortwo of these plates of magnetic material. All the retaining plates may,however, be made of strong bronze, or of a non-magnetic steel.

In Figs. 7, 8 and 18, and in other figures, I have indicated a modifiedconstruction in which the keys f for holding the end-connecting portionsof the windings extend longitudinally of the rotor, parallel with itsaxis, instead of circumferentially, as in Figs. 1 and (5. Theselongitudinal keys may therefore be merely extensions of the keys in thelongitudinal slots. T he circumferential endconnecting portions of thewinding are held in place by the longitudinal keys which cross abovethem. The portion of the core surface forming the pole piece ispreferably not slotted; but the retaining plates at the ends of the coremay be slotted and provided with shorter longitudinal keys extendingacross the series of retaining plates up to the end of the laminatediron core.

The winding of the rotor may be comoscd of many turns or of few turns asdered. In Fig. 8, and in other figures, there are twenty conductors ineach slot, connect ed in series, while in Fig. 1 there are in ellectfour heavy conductors in each slot, connected in series. As a matter offact, in Fig. 1 each of the four insulated conductors in the slotcomposed of two copper bars arranged side by side, .in contact. Thesecopper bars are wide and comparatively thin, and are arranged on edge inthe slot, the slot being deep enough to accommodate two layers of suchconductors, one above the other. The end-connections between suchconductors at may be made as indicated in Figs. 2, l and The ends of theinner conducting bars embedded on edge in the longitudinal channels arebent to lie circumferentially in the connecting channels at the ends ofthe rotor, and connection is made between different bars by bringingtheir flat sides together to form a lap joint, as indicated in 2 and 3,the joint being preferably screwed or riveted together and soldered.Where the end of a conductor bar it the top of one slot is to beconnected to a bar in a lower layer of the same slot, this may beaccomplished, as shown in Figs. i and 3, by bringing the tint sides ofthe bar into contact with a thin flat plate a wide enough to span themboth, the parts being made fast by solder and rivets. In i S T haveshown the top conductor in one slot and the bottom conductor in the nextslot connected by copper strips a which extend into a radial recess andare soldered together. Where the winding is to be made of many turns ofcomparatively small cross section, the conductors may be simply laid inthe continuous channels and worked into place.

In Fig. 16 l have indicated a means for compressing the windings moreclosely in the slots. After the coils are wound in place a heavy ring 9carrying radial set screws h It may be placed about the rotor and theset screws may then be tightened against blocks 7.; 7a lying over thewedge keys. If these keys are made in reasonably short sections, smallsupplemental keys 7 f can be driven into place above the shoulders ofthe main keys so as to occupy the space left when the main keys aredepressed. In Fig. 17 I have indicated one of the supplemental keyslying above the shoulder f of the main key. Different shapes of keys areshown in Fig. 16.

It will be evident that in the construction shown in Figs. 7 and 8,where the retaining keys all run longitudinally, the portions of thecircumferential slots lying between the longitudinal ribs, will beuncovered. In Figs. 18- and 19 I have illustrated a means for coveringthese intermediate portions of the circumferential slots by means offillerblocks on, such as shown in Fig. 19. These filler-blocks will beprovided with projecting ribs or shoulders m adapted to interlock withundercut grooves in the projecting portions of the plates on either sideof the slots, and they also have shoulders m adapted to overlie thelongitudinal keys and assist in holding said keys in place.

It will be observed that in the rotor of my invention the endconnectingportions a of the winding are held against centrifugal force byretaining members such as disks or plates 0 c which extend radiallyinward well toward the center. The centrifugal tension is thereforetransmitted radially and sustained by material near the center which isnot so greatly strained by its own centrifugal force as a mere bandencircling the outside of the rotor would be.

I claim:

1. A rotor having a series of longitudinal channels and circumferentialtransverse connecting grooves in its periphery, a winding having itsactive and inactive portions embedded in said channels and grooves,respectively, longitudinal keys overlying said longitudinal channels,and circumferential keys overlying said transverse grooves, whereby saidkeys retain said conductors in place against centrifugal force.

2.. A rotor having a series of longitudinal channels and circumferentialtransverse connecting-grooves in its periphery, the active andend-connecting portions of a winding being embedded in said channels andgrooves, and circumferential keys in the transverse grooves overlyingthe conductors therein and interlocking with the sides of said groovesto retain said conductors in place against centrifugal force.

3. A rotor having longitudinal channels in its periphery, a windingembedded in said channels, retaining plates at the end of the rotorextending radially between the end connecting portions of said windingand providing circumferential channels to re ceive and hold said endconnections, and circumferential retaining members overlying saidcircumferential channels to retain said end connections in place againstcentrifugal force.

4. A rotor having narrow conductor bars embedded on edge in longitudinalchannels, said channels being of a depth to receive two or more layersof said conductor-bars, transverse disks at the ends of the rotor, withcircumferential channels between said disks in which the ends of saidbars are bent to lie, connectionsbeing made between a bar in an upperlayer and one in a lower layer by means of a flat plate transverse tothe axis of the rotor to which the flat sides of said upper and lowerbars are secured.

5. In a rotor for electric machines, the combination with a core havinglongitudinal channels, a winding in said channels, end connections forsaid winding, retaining plates lying between the end-connections of thewindings, and keys for interlocking said plates and windings, theperipheral surface of said plates and keys being grooved, whereby theradiating surface is increased.

In witness whereof, I hereunto subscribe my name this twenty sixth dayof January A. D., 1907.

HENRY H. WAIT.

Witnesses:

GEORGE V. BAR'roN, GEORGE E. FOLK.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

